Studies of the relation between phase behavior and emulsification methods with nanoemulsion formation

Abstract

The main aim of this work was to study the relationship between the type of phases present during the emulsification process, the order of addition of components and the droplet size of the resulting emulsions. In this study, a pseudoternary water/poly(oxyethylene) nonionic surfactant/decane system was chosen as a model system to form oil-in-water emulsions at 25 °C. The phase behavior of the model system was determined at constant temperature in order to know the equilibrium phases and also those involved in the emulsification process. The low-energy emulsification methods studied were A. Addition of oil to an aqueous surfactant dispersion. B. Addition of water to a surfactant solution in oil. C. Mixing preequilibrated samples of the components.

Emulsion droplet size distributions were obtained by means of laser diffraction and scattering methods as well as by optical microscopy.

The emulsions obtained with methods A and C were more polydisperse than those obtained by method B. Furthermore, with method B very small droplet size emulsions, nanoemulsions, could be obtained. The results have been interpreted according to the changes in the natural curvature of the surfactants during the emulsification process.